Biology subjects

Andronache, A.

Publications and source records attributed to Andronache, A..

4 recordsLinked to original sources

bioRxiv2025

High-Throughput Screening Identifies PLK1 Inhibition as a Strategy to Potentiate BTK Blockade in Marginal Zone Lymphoma

B-cell receptor (BCR) signaling is a key therapeutic target in B-cell lymphomas, and Bruton tyrosine kinase inhibitors (BTKi) have demonstrated clinical efficacy in marginal zone lymphoma (MZL). However, the rate of complete remissions is relatively low, and resistance remains a significant clinical challenge, underscoring the need for novel combination strategies. To identify compounds that enhance the activity of BTKi and overcome resistance, we conducted a high-throughput screen of 1,695 compounds using a previously developed MZL model of acquired resistance to BTK and PI3K inhibitors derived from the Karpas1718 cell line. Thirty-three compounds showed single-agent anti-proliferative activity in the nanomolar range, both in the Karpas1718-resistant and parental cells. Based on their clinical potential in combination with BTKi, seven compounds were selected for further validation. The polo-like kinase 1 (PLK1) inhibitor rigosertib emerged as a top candidate, showing strong activity in both parental and BTKi-resistant cell lines. Combination treatment of rigosertib and BTKi zanubrutinib resulted in broad transcriptomic changes, characterized by the downregulation of pathways involved in B-cell activation, proliferation, and BCR signaling. Mechanistically, the combination reduced phosphorylation of key BCR pathway components and inhibited NF-{kappa}B nuclear translocation. These findings suggest that PLK1 inhibition can overcome BTKi resistance by further inhibiting BCR signaling through the canonical NF-{kappa}B pathway. Therefore, the dual pharmacological inhibition of BTK and PLK1 is a promising therapeutic approach for patients with MZL and warrants further preclinical and clinical investigations.

cancer biology↗

bioRxiv2024

CDK12 controls transcription at damaged genes and prevents MYC-induced transcription-replication conflicts

Oncogene-induced replicative stress is a potent tumor-suppressive mechanism that must be kept in check for cancer cells to thrive. Thus, the identification of genes and pathways involved in replicative stress is key to understand cancer evolution and to identify prospective therapeutic targets. Here, we investigated factors that modulate replicative stress upon deregulation of the MYC oncogene. We identified the cyclin-dependent kinase CDK12 as selectively required to prevent transcription-replication conflicts and the activation of a cytotoxic DNA-damage response (DDR). At the mechanistic level, CDK12 was recruited to damaged genes by PARP-dependent DDR-signaling and elongation-competent RNAPII. Once recruited, CDK12 repressed transcription by preventing the association of CDK9 with RNAPII. Either loss or chemical inhibition of CDK12 led to DDR-resistant transcription at damaged genes. Genome-wide profiling revealed that loss of CDK12 exacerbated transcription-replication conflicts in MYC-overexpressing cells and led to the accumulation of double-strand DNA breaks (DSBs), occurring preferentially between early- replicating regions and transcribed genes, organized in a co-directional head-to-tail orientation. Overall, our data demonstrate that CDK12 protects genome integrity by repressing transcription of damaged genes, which is required for proper resolution of DSBs at oncogene-induced transcription-replication conflicts. This provides a rationale that explains both how CDK12 deficiency can promote tandem duplications of early-replicated regions during tumor evolution, and how CDK12 targeting can exacerbate replicative-stress in tumors.

cancer biology↗

bioRxiv2023

Novel determinants of NOTCH1 trafficking and signaling in breast epithelial cells

The evolutionarily conserved Notch pathway controls cell-cell communication during development and in adult metazoans. It influences cell fate decisions, cell proliferation and cell differentiation, and contributes to the maintenance of normal tissue homeostasis. Consequently, misregulation of the Notch pathway is associated with a wide range of diseases, including congenital disorders and cancers with little to no cure. Signaling by Notch receptors is regulated by a complex set of cellular processes that include maturation and trafficking to the plasma membrane, endocytic uptake and sorting, lysosomal and proteasomal degradation, and ligand-dependent and independent proteolytic cleavages. We devised assays to follow quantitively the lifetime of endogenous human NOTCH1 receptor in breast epithelial cells in culture. Based on such analysis, we executed a high-content screen of 2749 human genes for which modulatory compounds exist, to identify new regulators of Notch signaling activation that might be amenable to pharmacologic intervention. We uncovered 39 new NOTCH1 genetic modulators that affect different steps of NOTCH1 cellular dynamics. In particular, we find that PTPN23 and HCN2 act as positive NOTCH1 regulators by promoting endocytic trafficking and NOTCH1 maturation in the Golgi apparatus, respectively, while SGK3 serves as a negative regulator that can be modulated by pharmacologic inhibition. Our findings might be relevant in the search of new strategies to counteract pathologic Notch signaling.

cell biology↗

bioRxiv2019

An early Myc-dependent transcriptional program underlies enhanced macromolecular biosynthesis and cell growth during B-cell activation

Upon activation, lymphocytes exit quiescence and undergo substantial increases in cell size, accompanied by activation of energy-producing and anabolic pathways, widespread chromatin decompaction and elevated transcriptional activity. These changes depend upon prior induction of the Myc transcription factor, but how Myc controls them remains unclear. We addressed this issue in primary mouse B-cells, based on conditional deletion of the c-myc gene, followed by LPS stimulation. Myc was rapidly induced, became detectable on virtually all active promoters and enhancers, but had no direct impact on global transcriptional activity. Instead, Myc contributed to the swift up- and down-regulation of several hundred genes, including many known regulators of the aforementioned cellular processes. Myc-activated promoters were enriched for E-box consensus motifs, bound Myc at the highest levels and showed enhanced RNA Polymerase II recruitment, the opposite being true at down-regulated loci. Remarkably, the Myc-dependent signature identified in activated B-cells was also enriched in Myc-driven B-cell lymphomas: hence, besides modulation of new cancer-specific programs, the oncogenic action of Myc may largely rely on sustained deregulation of its normal physiological targets.

cancer biology↗